There are a variety of fluid dispensers in the prior art. Fluid dispenser components typically comprise: a reservoir, a means for regulating fluid flow, and an applicator. The reservoir contains a fluid and also has a means for motivating the fluid to communicate into the means for regulating the fluid flow and further communicating to the applicator. The means for motivating the fluid out of the reservoir can be anything from simply using gravity to having a means for increasing the pressure of the fluid in the reservoir thus motivating the fluid to flow out of the reservoir through the means for regulating the fluid flow and onward to the applicator. The means for motivating the fluid out of the reservoir outside of simply using gravity can include using a movable piston inside of a close fitting bore such as in a hypodermic needle, or having a reservoir constructed of a resilient material wherein the reservoir is compressed in some manner to reduce its interior volume thus raising the pressure of the fluid in the reservoir. The means for regulating the fluid flow can include simply having a selectively sized fluid flow passageway, or a valve of some type. The applicator portion of the fluid dispenser can include a pen quill, a hollow needle being a cannula with a lumen, a brush with bristles, or a sponge type material, and the like.
There are many issues surrounding the fluid dispenser, such as accurate controlling of the measured volumes of the fluid dispensed, how to handle the many different types of fluids and their properties, such as viscosity, miscibility of the various fluid components, and the drying or hardening characteristics of the fluid as it flows through the applicator and onto the desired surface, area, or volumemetric cavity at the desired location. Other issues for fluid dispensers would include fluid waste, spillage, leakage, and reuse of the fluid dispenser after a period of inactivity wherein the fluid may dry or harden in or on any of the fluid dispenser components. Typically, once the fluid leaves the sealed reservoir it is exposed to atmospheric air wherein the fluid's volatile compounds start to evaporate and initiate the fluid drying or hardening process which may cause fluid communication problems for the fluid dispenser components being the means to regulate fluid flow and the applicator as the fluid viscosity greatly increases and can essentially cause the fluid dispenser to become inoperative. Also, another issue is the communication of the fluid to the applicator itself, such as with a conventional brush that is dipped into a fluid wherein the fluid is deposited all over the brush which typically causes an excess amount of fluid on the brush requiring at least one brush stroke to remove excess fluid from the brush before use, with typically only one side of the brush which will be applied to the surface and the like. In addition, reservoir breakage and accidental discharge of the fluid can be problems while the fluid dispenser is in use.
In addressing the above-identified issues that are common to fluid dispensers, the prior art discloses a number of different types of apparatus. Starting with the at accurate controlling of the measured volume of fluid to be dispensed, a common solution is to utilize a movable piston in a close fitting bore while closely controlling the axial movement of the piston with graduations marked on the outside of a translucent of clear bore, thus controlling the axial displacement or volume reduction in the reservoir as is common with a hypodermic needle assembly. Another method of controlling the volume of the fluid to be dispensed is to simply size the reservoir volumetrically to contain the desired volume of fluid to be dispensed, which would make the reservoir a single use system that may be disposable if it is not refillable, such as with a common eyedropper assembly. A further method of controlling the volume of fluid to be dispensed is to use a resilient reservoir having an additional apparatus of mechanical stops or a control upon the amount of resilient reservoir volume reduction, such as disclosed in U.S. Pat. No. 5,186,563 to Gebhard et al. and U.S. Pat. No. 4,944,625 to Futter et al. The complexity of the apparatus to control the volume of fluid to be dispensed depends to a large degree upon the volumetric accuracy required, with the piston and bore apparatus being substantially the most accurate, however, having a higher cost to manufacture and also having the attendant disadvantage of requiring a close fitting dynamic fluid seal between the piston and the bore. Also, utilizing a specifically sized volume of reservoir to dispense a selected amount of fluid can result in material waste in the form of making the reservoirs' individually disposable for a single use, or adding additional apparatus to make the reservoir refillable for multiple uses from one reservoir. The use of a resilient reservoir is appealing due to lower cost and simplicity; however, the addition of apparatus to create some sort of mechanical stop or stops can also add complexity and cost to the fluid dispenser assembly.
Further, looking to the fluid dispenser issue of controlling or the regulating the flow of the fluid as it exits the reservoir and communicates to the applicator, the prior art typically utilizes a valve of some type as is typically disclosed in U.S. Pat. No. 4,470,715 to Reuchlin et al., U.S. Pat. No. 6,056,470 to Nchashi et al., and U.S. Pat. No. 6,402,410 to Hall et al. Alternatively, a fluid flow restriction such as an orifice or the lumen inside of the cannula wherein the fluid dispensed must flow through the orifice or the lumen inside of the cannula is disclosed in U.S. Pat. No. 1,945,957 to Salmon and U.S. Pat. No. 1,935,639 to Keeshan. Obviously, for simplicity the orifice or the lumen would be the most attractive apparatus use for controlling and regulating the flow of fluid, however, the disadvantage of the orifice or the lumen would be the lack of the ability to substantially stop the flow of a fluid when it is desired to prevent spillage or leakage. The use of a valve can accommodate this requirement, however, a valve adds a degree of mechanical complexity that is generally undesirable. The prior art has recognized this problem and has attempted to solve it by making the reservoir and the means for controlling and regulating the flow of fluid as separable pieces, creating the ability to separately clean the means for controlling and regulating the flow of fluid, such as typically disclosed in U.S. Pat. No. 4,447,169 to Vartoughian. Adding the requirement that if the means for controlling and regulating the flow of fluid were removed from the reservoir requires that the reservoir outlet would have to be sealable, which of course again requires a valve or cap to substantially seal reservoir outlet as disclosed in U.S. Pat. No. 3,969,028 to Negreiros, U.S. Pat. No. 3,592,202 to Jones, and U.S. Pat. No. 5,975,088 to Stehman. This causes the attendant problems of when the fluid dries or hardens after exposure to atmospheric air, the valve or the cap will tend to gum up or stick causing difficulty in initiating reuse of the fluid dispenser for having the fluid flow out of the reservoir outlet and into the means for regulating fluid flow, and finally to the applicator.
What is needed is a fluid dispenser that overcomes the previously identified issues related to fluid dispensers, being selectable volumes of fluid to dispense from the reservoir, the means of controlling or regulating the fluid flow, having reduced susceptibility to the fluid drying or hardening from exposure to atmospheric air, the method of applying the fluid to the applicator, and having the reservoir separable from the means of controlling the regulating the fluid flow. While at the same time keeping the objectives of simplicity, function and minimal manufacturing cost paramount. This requires a reservoir that has an easily controllable interior volume adjustment with reduced risk of rupture, breakage, or leakage of the reservoir fluid and with the reservoir having a resealable outlet that minimizes the problems of the fluid drying or hardening that would restrict the fluid communicating from the reservoir outlet that is caused from the fluid being exposed to atmospheric air while the same time reducing the risk of accidental spillage of the fluid from the reservoir. Also, this would require that the means of controlling and regulating the fluid flow would deposit the fluid to an interior portion of the applicator thus minimizing the need for removal of excess fluid from the applicator prior to use.